Not really an addendum, since I haven’t written any of this myself, just some links to very interesting texts about Facebook and what it is all about. They come as a nice addition to the original post and the discussion that it sparked.
http://www.guardian.co.uk/technology/2008/jan/14/facebook
(why Facebook is evil at its core)
http://mollyschoemann.com/2009/01/01/why-i-left-facebook/
(why Facebook is detached from reality)
http://wrathfulindifference.com/2009/01/08/in-defense-of-facebook/
(why Facebook has its uses)